posted on 2019-12-10, 20:43authored byQiushi Zhang, Yunsong Pang, Jarrod Schiffbauer, Aleksandar Jemcov, Hsueh-Chia Chang, Eungkyu Lee, Tengfei Luo
Precise spatiotemporal control of surface bubble movement
can benefit
a wide range of applications like high-throughput drug screening,
combinatorial material development, microfluidic logic, colloidal
and molecular assembly, and so forth. In this work, we demonstrate
that surface bubbles on a solid surface are directed by a laser to
move at high speeds (>1.8 mm/s), and we elucidate the mechanism
to
be the depinning of the three-phase contact line (TPCL) by rapid plasmonic
heating of nanoparticles (NPs) deposited in situ during bubble movement.
On the basis of our observations, we deduce a stick–slip mechanism
based on asymmetric fore–aft plasmonic heating: local evaporation
at the front TPCL due to plasmonic heating depins and extends the
front TPCL, followed by the advancement of the trailing TPCL to resume
a spherical bubble shape to minimize surface energy. The continuous
TPCL drying during bubble movement also enables well-defined contact
line deposition of NP clusters along the moving path. Our finding
is beneficial to various microfluidics and pattern writing applications.